Selective Chemical Fining of Small Bubbles in Glass

ABSTRACT

A method of fining glass is disclosed that includes flowing a molten glass bath through a fining chamber. The molten glass bath has an undercurrent that flows beneath a skimmer that is partially submerged in the molten glass bath. One or more fining agents are introduced into the undercurrent of the molten glass bath directly beneath the skimmer from a carrier gas. In this way, the fining agent(s) may selectively target the gas bubbles drawn under the skimmer within the undercurrent of the molten glass for removal. The method may be employed to fine molten gas produced in a submerged combustion melter. A fining vessel for fining molten glass is also disclosed.

The present disclosure is directed to glass fining and, morespecifically, to techniques for targeting and selectively exposing smallbubbles, which might otherwise be too small to quickly ascend to theglass surface, to a fining agent.

BACKGROUND

Glass is a rigid amorphous solid that has numerous applications.Soda-lime-silica glass, for example, is used extensively to manufactureflat glass articles including windows, hollow glass articles includingcontainers such as bottles and jars, and also tableware and otherspecialty articles. Soda-lime-silica glass comprises a disordered andspatially crosslinked ternary oxide network of SiO₂—Na₂O—CaO. The silicacomponent (SiO₂) is the largest oxide by weight and constitutes theprimary network forming material of soda-lime-silica glass. The Na₂Ocomponent functions as a fluxing agent that reduces the melting,softening, and glass transition temperatures of the glass, as comparedto pure silica glass, and the CaO component functions as a stabilizerthat improves certain physical and chemical properties of the glassincluding its hardness and chemical resistance. The inclusion of Na₂Oand CaO in the chemistry of soda-lime-silica glass renders thecommercial manufacture of glass articles more practical and less energyintensive than pure silica glass while still yielding acceptable glassproperties. Soda-lime-silica glass, in general and based on the totalweight of the glass, has a glass chemical composition that includes 60wt % to 80 wt % SiO₂, 8 wt % to 18 wt % Na₂O, and 5 wt % to 15 wt % CaO.

In addition to SiO₂, Na₂O, and CaO, the glass chemical composition ofsoda-lime-silica glass may include other oxide and non-oxide materialsthat act as network formers, network modifiers, colorants, decolorants,redox agents, or other agents that affect the properties of the finalglass. Some examples of these additional materials include aluminumoxide (Al₂O₃), magnesium oxide (MgO), potassium oxide (K₂O), carbon,sulfates, nitrates, fluorines, chlorines, and/or elemental or oxideforms of one or more of iron, arsenic, antimony, selenium, chromium,barium, manganese, cobalt, nickel, sulfur, vanadium, titanium, lead,copper, niobium, molybdenum, lithium, silver, strontium, cadmium,indium, tin, gold, cerium, praseodymium, neodymium, europium,gadolinium, erbium, and uranium. Aluminum oxide is one of the morecommonly included materials—typically present in an amount up to 2 wt %based on the total weight of the glass—because of its ability to improvethe chemical durability of the glass and to reduce the likelihood ofdevitrification. Regardless of what other oxide and/or non-oxidematerials are present in the soda-lime-glass besides SiO₂, Na₂O, andCaO, the sum total of those additional materials is preferably 10 wt %or less, or more narrowly 5 wt % or less, based on the total weight ofthe soda-lime-silica glass.

The manufacture of glass involves melting a vitrifiable feed material(sometimes referred to as a glass batch) in a furnace or melter within alarger volume of molten glass. The vitrifiable feed material may includevirgin raw materials, recycled glass (i.e., cullet), glass precursoroxides, etc., in proportions that result in glass having a certain glasscomposition upon melting and reacting of the feed material. When thevitrifiable feed material is melted into glass, gas bubbles of varioussizes are typically produced and become entrained within the glass. Theproduction of gas bubbles is especially pronounced if the vitrifiablefeed material is melted in a submerged combustion melter that includessubmerged burners positioned to fire their combustion products directlyinto the glass melt. The quantity of gas bubbles entrained within theglass may need to be reduced to satisfy commercial specifications for“bubble free” glass. The removal of gas bubbles—a process known as“fining”—may be warranted for various reasons including the visualappearance of the glass when cooled and formed into a finishedcommercial article such as a glass container, flat glass product, ortableware. Glass fining has traditionally been accomplished by heatingthe glass to achieve a glass viscosity more conducive to bubbleascension and/or by adding a fining agent into the glass.

A fining agent is chemical compound that reacts within the glass atelevated temperatures to release fining gases such as O₂, SO₂, and/orpossibly others into the glass. The fining gases help eradicate smallergas bubbles that result from melting of the vitrifiable feed materialother than those attributed to the fining agent (“native bubbles”). Thefining gases, more specifically, form new gas bubbles (“fining bubbles”)and/or dissolve into the glass melt. The fining bubbles rapidly ascendto the surface of the glass—where they ultimately exit the glass meltand burst—and during their ascension may sweep up or absorb the smallernative gas bubbles along the way. The fining gases that dissolve intothe glass melt may diffuse into the smaller native bubbles to increasethe size and the buoyancy rise rate of those bubbles. The fining gasesmay also change the redox state [(Fe²⁺/(Fe²⁺+Fe³⁺) in which Fe²⁺ isexpressed as FeO and Fe³⁺ is expressed as Fe₂O₃] of the glass and causesome of the smaller native bubbles to disappear as the gas(es) in thosebubbles dissolves into the glass melt. Any one or a combination of thesemechanisms may be attributed to the fining agent.

A fining agent has traditionally been added to the vitrifiable feedmaterial or metered separately into the glass. Whether the fining agentis included in the vitrifiable feed material or added separately, theresultant fining gases interact indiscriminately with gas bubbles of allsizes within the glass. Such broad exposure of the fining gases to allgas bubbles is somewhat inefficient since the larger native bubbles willquickly ascend through the glass and burst on their own regardless ofwhether a fining agent is added to the glass. Additionally, if thefining agent is introduced separately from the vitrifiable feedmaterial, mechanical stirring may be used to uniformly mix the finingagent throughout the glass. But stirring the glass breaks larger nativebubbles into smaller gas bubbles and counteracts the fining process bydrawing bubbles (both large and small) back down into the glass awayfrom the surface of the glass. As such, to clear the glass of bubbles,the amount of the fining agent added to the glass is usually based onthe total amount of native gas bubbles that may be contained in theglass even though the smaller native bubbles dictate how much time isrequired to fine the glass since those bubbles ascend through the glassat the slowest pace or do not ascend at all.

The current practices of unselectively introducing a fining agent intothe glass requires the consumption of an excess amount of the finingagent. This can increase the cost of materials as well as the operatingcosts associated with the fining process. Moreover, the fining processis not as optimized as it could be due to the oversupply of the finingagent and the corresponding fining activity that must be supported,which results in additional fining time beyond what is theoreticallyrequired to remove only the smaller native bubbles. The presentdisclosure addresses these shortcomings of current fining procedures byselectively exposing the smaller native bubbles in the glass to one ormore fining agents. The targeted exposure of smaller native bubbles tothe fining agent(s) may reduce the need to add excessive amounts of thefining agent to the glass, thus saving material and energy costs, andmay also speed the overall fining process since the fining gasesintroduced into the glass can be minimized while still targeting andremoving the smaller native bubbles. The fining agent(s) do notnecessarily have to be exposed to the larger native bubbles since doingso is unlikely to have a noticeable impact on the amount of time ittakes to fine the glass.

SUMMARY OF THE DISCLOSURE

The present disclosure is directed to an apparatus and method for finingglass. The apparatus is a fining vessel that receives an input moltenglass. The input molten glass has a first density and a firstconcentration of entrained gas bubbles. The fining vessel may be astand-alone tank that receives the input molten glass from a separatemelter, such as a submerged combustion melter, or it may be part of alarger Siemens-style furnace that receives the input molten glass froman upstream melting chamber. The input molten glass is combined with andsubsumed by a molten glass bath contained within a fining chamberdefined by a housing of the fining vessel. The molten glass bath flowsthrough the fining chamber along a flow direction from an inlet to anoutlet of the fining vessel. Output molten glass is discharged from thefining vessel after flowing through the fining chamber. The outputmolten glass has a second density that is greater than the first densityand a second concentration of entrained gas bubbles that is less thanthe first concentration of entrained gas bubbles. To facilitate finingof the glass, a skimmer is partially submerged in the molten glass bath.The skimmer defines a submerged passageway together with correspondingportions of the housing of the fining vessel. An undercurrent of themolten glass bath flows through the submerged passageway and is exposedto one or more fining agents beneath the skimmer to better targetsmaller gas bubbles for removal.

The present disclosure embodies a number of aspects that can beimplemented separately from or in combination with each other. Accordingto one embodiment of the present disclosure, a method of fining glassincludes several steps. One step involves supplying input molten glassinto a fining chamber of a fining vessel. The input molten glasscombines with a molten glass bath contained within the fining chamberand introduces entrained gas bubbles into the molten glass bath. Theinput molten glass has a density and a concentration of gas bubbles.Another step of the method involves flowing the molten glass baththrough the fining chamber in a flow direction. The molten glass bathhas an undercurrent that flows beneath a skimmer, which is partiallysubmerged in the molten glass bath, and through a submerged passagewaydefined in part by the skimmer. Still another step of the methodinvolves introducing a carrier gas into the undercurrent of the moltenglass bath directly beneath the skimmer. The carrier gas comprisessuspended particles of one or more fining agents.

According to another aspect of the present disclosure, a method ofproducing and fining glass includes several steps. One step involvesdischarging combustion products from one or more submerged burnersdirectly into a glass melt contained within an interior reaction chamberof a submerged combustion melter. The combustion products dischargedfrom the one or more submerged burners agitate the glass melt. Anotherstep of the method involves discharging foamy molten glass obtained fromthe glass melt out of the submerged combustion melter. Still anotherstep of the method involves supplying the foamy molten glass into afining chamber of a fining vessel as input molten glass. The inputmolten glass combines with a molten glass bath contained within thefining chamber and introduces entrained gas bubbles into the moltenglass bath. The input molten glass has a density and comprises up to 60vol % bubbles. Another step of the method involves flowing the moltenglass bath through the fining chamber in a flow direction. The moltenglass bath has an undercurrent that flows beneath a skimmer, which ispartially submerged in the molten glass bath, and through a submergedpassageway defined in part by the skimmer. Yet another step of themethod involves introducing a carrier gas into the undercurrent of themolten glass bath directly beneath the skimmer. The carrier gascomprises suspended particles of one or more fining agents. And stillanother step of the method involves discharging output molten glass fromthe fining vessel. The output molten glass has a density that is greaterthan the density of the input molten glass and further comprises lessthan 1 vol % bubbles.

According to yet another aspect of the present disclosure, a finingvessel for fining glass includes a housing that defines a finingchamber. The housing has a roof, a floor, and an upstanding wall thatconnects the roof and the floor. The housing further defines an inlet tothe fining chamber and an outlet from the fining chamber. The finingvessel also includes a skimmer that extends downwards from the roof ofthe housing towards the floor of the housing and further extends acrossthe fining chamber between opposed lateral sidewalls of the upstandingwall. The skimmer has a distal free end that together with correspondingportions of the floor and upstanding wall defines a submergedpassageway. Moreover, a plurality of nozzles are supported in the floorof the housing directly beneath the skimmer. Each of the nozzles isconfigured to dispense a carrier gas into the fining chamber. Thecarrier gas includes a main gas that contains suspended particles of oneor more fining agents.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure, together with additional objects, features, advantages,and aspects thereof, will be best understood from the followingdescription, the appended claims, and the accompanying drawings, inwhich:

FIG. 1 is an elevated cross-sectional representation of a submergedcombustion melter and a fining vessel that receives molten glassproduced by the submerged combustion melter according to one embodimentof the present disclosure;

FIG. 2 is a cross-sectional plan view of the floor of the submergedcombustion melter illustrated in FIG. 1 and taken along section line2-2;

FIG. 3 is an elevated cross-sectional illustration of the fining vesseldepicted in FIG. 1 according to one embodiment of the presentdisclosure;

FIG. 4 is a cross-sectional plan view of the fining vessel depicted inFIG. 3 and taken along section line 4-4;

FIG. 5 is a magnified elevated cross-sectional view of a portion of thefining vessel shown in FIG. 3 including a skimmer positioned within thefining vessel;

FIG. 6 is cross-sectional view of the fining vessel taken along sectionlines 6-6 in FIG. 5;

FIG. 7 is a magnified view of the skimmer illustrated in FIG. 5; and

FIG. 8 is a flow diagram of a process for forming glass containers fromthe output molten glass discharged from the fining vessel according toone embodiment of the present disclosure.

DETAILED DESCRIPTION

The disclosed apparatus and fining method are preferably used to finemolten glass produced by melting a vitrifiable feed material viasubmerged combustion melting. As will be described in further detailbelow, submerged combustion melting involves injecting a combustible gasmixture that comprises fuel and an oxidant directly into a glass meltcontained in a submerged combustion melter though submerged burners. Thecombustible gas mixture autoignites and the resultant combustionproducts cause vigorous stirring and turbulence as they are dischargedthrough the glass melt. The intense shearing forces experienced betweenthe combustion products and the glass melt cause rapid heat transfer andparticle dissolution throughout the glass melt. While submergedcombustion technology can melt and integrate a vitrifiable feed materialinto the glass melt relatively quickly, thus resulting in relatively lowglass residence times, the glass melt tends to be foamy and have arelatively low density despite being chemically homogenized whendischarged from the melter. Fining foamy molten glass discharged fromthe glass melt in accordance with the present disclosure can render thefining process more efficient. Of course, molten glass produced in othertypes of melting apparatuses, including a melting chamber of aconventional Siemens-style furnace, may also be fined in the same way.

Referring now to FIGS. 1-7, a glass fining vessel 10 is depictedaccording to one embodiment of the present disclosure. The glass finingvessel 10 receives an input molten glass 12 that originates from withina submerged combustion melter 14 and discharges output molten glass 16for additional processing into a finished article. The glass finingvessel 10 has a housing 18 that defines a fining chamber 20 in which amolten glass bath 22 is contained. The housing 18 further defines aninlet 24 through which the input molten glass 12 is received and anoutlet 26 through which the output molten glass 16 is discharged. Theinput molten glass 12 combines with and is subsumed by the molten glassbath 22, and the output molten glass 16 is drawn from the molten glassbath 22 at a location downstream from the inlet 24. As such, the moltenglass bath 22 flows through the fining chamber 20 in a flow direction Ffrom the inlet 24 to the outlet 26 of the glass fining vessel 10 whilebeing fined along the way as described in more detail below.

The housing 18 of the glass fining vessel 10 includes a roof 28, a floor30, and an upstanding wall 32 that connects the roof 28 and the floor30. The upstanding wall 32 typically includes an inlet or front end wall32 a, an outlet or back end wall 32 b, and two opposed lateral sidewalls32 c, 32 d that join the inlet end and outlet end walls 32 a, 32 b. Thehousing 18 of the fining vessel 10 is constructed from a one or morerefractory materials. Refractory materials are a class of inorganic,non-metallic materials that can withstand high-temperatures whileremaining generally resistant to thermal stress and corrosion. In oneparticular embodiment, the floor 30 and the glass-contacting portions ofthe upstanding wall 32 may be formed from fused cast AZS(alumina-zirconia-silicate), bond AZS, castable AZS, high alumina,alumina-chrome, or alumina-silica type refractories. Insulating bricksand ceramic fire boards may be disposed behind these portions of thehousing 18. As for the roof 28 and the superstructure (i.e., thenon-glass contacting portion of the upstanding wall 32), those portionsof the housing 18 may be formed from an alumina-silica refractory suchas mullite.

The inlet 24 to the fining vessel 10 may be defined in the roof 28 ofthe housing 18 proximate the inlet end wall 32 a, as shown, although itmay also be defined in the inlet end wall 32 a either above or below asurface 34 of the molten glass bath 22 or in one or both of the lateralsidewalls 32 c, 32 d either above or below the surface 34 of the moltenglass bath 22. The inlet 24 provides an entrance to the fining chamber20 for the introduction of the input molten glass 12 at a feed rate RF.The inlet 24 may be fluidly coupled to the submerged combustion melter14 or an intermediate holding tank (not shown) located between thesubmerged combustion melter 14 and the fining vessel 10 by a containedconduit or, in another implementation, such as the one illustrated here,the inlet 24 may be positioned in flow communication with the inputmolten glass 12 so that the input molten glass 12 can be poured into thefining chamber 20 while being exposed to the ambient environment. Anexample of an intermediate holding tank that may be fluidly positionedbetween the submerged combustion melter 14 and the fining vessel 10 isthe stilling vessel that is disclosed in a patent application titledSTILLING VESSEL FOR SUBMERGED COMBUSTION MELTER and having Docket No.19522, which is assigned to the assignee of the present invention and isincorporated herein by refererence in its entirety.

The outlet 26 of the fining vessel 10 may be defined in the outlet endwall 32 b either adjacent to the floor 30 (as shown) or above the floor30 yet beneath the surface 34 of the molten glass bath 22. The outlet 26may also be defined in the floor 30 or in one or both of the lateralsidewalls 32 c, 32 d beneath the surface 34 of the molten glass bath 22and proximate the outlet end wall 32 b. The outlet 26 provides an exitfrom the fining chamber 20 for the discharge of the output molten glass16 at a discharge or pull rate RD. In the context of commercial glasscontainer manufacturing, the outlet 26 of the fining vessel 10 mayfluidly communicate with a spout chamber 36 of a spout 38 appended tothe outlet end wall 32 b. The spout 38 includes a spout bowl 40, whichdefines the spout chamber 36 along with an orifice plate 42, and furtherincludes at least one reciprocal plunger 44 that reciprocates to controlthe flow of accumulated output molten glass 46 held within the spoutchamber 36 through an aligned orifice 48 in the orifice plate 42 tofashion streams or runners of glass. These streams or runners of glassmay be sheared into glass gobs of a predetermined weight that can beindividually formed into glass containers upon delivery to glasscontainer forming machine.

The fining vessel 10 includes a skimmer 50 positioned between the inlet24 and the outlet 26. The skimmer 50 is formed of a refractory materialsuch as the refractories disclosed above for the glass-contactingportions of the upstanding wall 32. As shown best in FIGS. 5 and 7, theskimmer 50 extends downwardly from the roof 28 of the housing 18 and ispartially submerged in the molten glass bath 22. At least a submergedportion 52 of the skimmer 50 extends across the fining chamber 20between the lateral sidewalls 32 c, 32 d of the housing 18 and has anupstream face 54, an opposite downstream face 56, and a distal free end58 connecting the upstream and downstream faces 54, 56. The distal freeend 58 of the skimmer 50 is separated from the floor 30 of the housing18 by a distance T_(D) and, consequently, defines a submerged passageway60 along with corresponding portions of the floor 30 and the sidewalls32 c, 32 d. The establishment of the submerged passageway 60 causes anundercurrent 62 of the molten glass bath 22 to flow beneath the skimmer50 and through the submerged passageway 60 as the glass bath 22 as awhole flows along the flow direction F towards the outlet 26 of thefining vessel 10. The skimmer 50 has a centerplane 64 that is parallelto a vertical reference plane 66, which is perpendicular to thehorizontal or gravity level, or angled at no more than 5° from thevertical reference plane 66 in either direction.

At least one fining agent is introduced into the molten glass bath 22directly beneath the skimmer 50 in direct exposure to the undercurrent62 of the molten glass bath 22. The fining agent(s) are delivered by acarrier gas 68 in which one or more fining agents are suspended as aparticulate. The term “directly beneath the skimmer” as used hereinrefers to a zone 70 (FIG. 7) of the fining chamber 20 defined bysectioning the skimmer 50 where its thickness S_(T) as measured betweenthe upstream face 54 and the downstream face 56 is greatest, and thenextending first and second planes 70 a, 70 b from the upstream anddownstream faces 54, 56 of the skimmer 50 where sectioned, respectively,parallel with the centerplane 64 of the skimmer 50 such that the planes70 a, 70 b intersect the floor 30 and the upstanding wall 32 of thehousing 18. The volume between the skimmer 50, the floor 30, thesidewalls 32 c, 32 d, and the extended planes 70 a, 70 b is the zone 70that is considered to be directly beneath the skimmer 50. By introducingat least one fining agent into this zone 70, smaller gas bubbles canmore easily be targeted for removal.

The carrier gas 68 may be introduced into the glass melt 22 directlybeneath the skimmer 50 through a plurality of nozzles 72 supported incorresponding openings defined in the floor 30 of the housing 18. Eachof the nozzles 72 has a feeder line 74 that fluidly communicates with acarrier gas supply conduit 76. The carrier gas supply conduit 76supplies the carrier gas 68 from a source (not shown) of the gas 68external to the fining vessel 10 at an appropriate pressure to ensurethat the carrier gas 68 can be dispensed through the glass melt 22.Preferably, to help ensure good exposure of the undercurrent 62 to thecarrier gas 68, the gas supply conduit 76 runs along a width W of thefining chamber 20 (FIG. 4) between the lateral sidewalls 32 c, 32 d andbeneath the distal free end 58 of the skimmer 50 within the zone 70under the skimmer 50, and the nozzles 72 are spaced apart across thewidth W of the fining chamber 20 to provide a row of carrier gaseffervescence that extends transverse to the flow direction F of themolten glass bath 22 and rises upwards from the floor 30 of the housing18, as depicted in FIG. 6. To help position the carrier gas supplyconduit 76 and the nozzles 72 directly beneath the skimmer 50, thecarrier gas supply conduit 76, the feeder lines 74, and the nozzles 72may be contained within a refractory support block 78 that is receivedin a channel 80 defined in the floor 30 of the housing 18. The channel80, as shown, may extend across the width W of the fining chamber 20,and the support block 78 may be slidable from one sidewall 32 c, 32 d tothe other sidewall 32 c, 32 d for easy insertion and removal.

The carrier gas 68 includes a main gas that supports the particles ofthe one or more fining agents. The main gas may be air or anothernon-dissolvable gas including, for example, nitrogen. The one or morefining agents suspended in the main gas may be any compound or acombination of compounds that release fining gases into the molten glassbath 22 when exposed to the thermal environment of the molten gas bath22. In particular, the fining agent(s) may include a sulfate such assodium sulfate (salt cake), which decomposes to release O₂ and SO₂ asthe fining gases. Other fining agents that may be carried in the carriergas 68 include Cr₂O₃, WO₃, or reactive carbon, aluminum, a carbonate,silicon carbide (SiC), oxidized metal powder, and combinations thereof.The particles of the fining agent(s) may be sized to ensure that theyare suspendable within and transportable by the main gas of the carriergas 68. For instance, the particles of the fining agent(s) may haveparticle sizes in which a largest particle dimension ranges from 0.05 mmto 5 mm or, more narrowly, from 0.1 mm to 1 mm. The particles of thefining agent(s) may also constitute anywhere from 1 vol % to 30 vol % ofthe carrier gas 68. The particles of the fining agents(s) are preferablythe only particulate matter included within the carrier gas 68 to avoidupsetting the local chemistry of the molten glass bath 22.

The skimmer 50 may separate gas bubbles 82 introduced into the moltenglass bath 22 by the input molten glass 12 according to the size of thegas bubbles 82. As discussed above, the input molten glass 12 containsbubbles of various sizes as a result of melting the vitrifiable feedmaterial in the submerged combustion melter 14. The input molten glass12 has a first density and first concentration of entrained gas bubbles.Here, as a result of submerged combustion melting, the input moltenglass 12 typically has a density between 0.75 gm/cm³ and 1.5 gm/cm³, ormore narrowly between 0.99 gm/cm³ and 1.3 gm/cm³, and a concentration ofentrained gas bubbles ranging from 30 vol % to 60 vol % forsoda-lime-silica glass. The gas bubbles carried within the input moltenglass 12 and added to the molten glass bath 22 have a diameter thattypically ranges from 0.10 mm to 0.9 mm and, more narrowly, from 0.25 mmto 0.8 mm. Compared to gas bubbles having a diameter of greater than 0.7mm, gas bubbles having a diameter of 0.7 mm or less are more likely toremain suspended in the deeper regions of the molten glass bath 22 asthe molten glass bath 22 flows along the flow direction F. The densityand bubble concentration values stated above may be different. Forexample, if the input molten glass 12 is obtained from a Siemens-stylemelting furnace, the density and bubble concentration values wouldlikely be greater than, and less than, the above-stated ranges,respectively, for soda-lime-silica glass.

The skimmer 50 can be sized and positioned to achieve the desiredseparation of the gas bubbles 82. Each of the following three designcharacteristics of the skimmer 50 effects the size of the bubbles thatpass beneath the skimmer 50 and through the submerged passageway 60: (1)a distance S_(D) between the centerplane 64 of the skimmer 50 at theaxial free end 58 and the inlet end wall 32 a along the flow directionF; (2) the distance T_(D) between the free end 58 of the skimmer 50 andthe floor 30 of the housing 18; and (3) the discharge rate R_(D) of theoutput molten glass 16 through the outlet 26 of the fining vessel 10. Byincreasing the distance S_(D) between the skimmer 50 and the inlet endwall 32 a (characteristic 1 above), the bubbles 82 have more time toascend to the surface 34 of the molten glass batch 22 and burst beforereaching the upstream face 54 of the skimmer 50. Likewise, decreasingthe distance S_(D) between the skimmer 50 and the inlet end wall 32 aprovides the bubbles 82 with less time to ascend to the surface 34 ofthe molten glass bath 22 and burst. Accordingly, the size of the gasbubbles 82 that are drawn under the skimmer 50 within the undercurrent62 tends to decrease as the distance S_(D) between the skimmer 50 andthe inlet end wall 32 a increases.

Additionally, the size of the gas bubbles 82 that are drawn under theskimmer 50 within the undercurrent 62 tends to decrease as the distanceT_(D) between the free end 58 of the skimmer 50 and the floor 30 of thehousing 18 (characteristic 2 above) decreases, and vice versa. Indeed,as the distance T_(D) between the free end 58 of the skimmer 50 and thefloor 30 decreases, the skimmer 50 is submerged deeper into the moltenglass bath 22 and the size of the gas bubbles 82 that are drawn underthe skimmer 50 within the undercurrent 62 also decreases. Conversely, asthe distance T_(D) between the free end 58 of the skimmer 50 and thefloor 30 increases, the skimmer 50 is submerged shallower into themolten glass bath 22, and the size of the gas bubbles 82 being drawnunder the skimmer 50 within the undercurrent 62 increases since moltenglass closer to the surface 34 of the molten glass bath 22 can now flowbeneath the skimmer 50. Lastly, a higher discharge rate R_(D) of theoutput molten glass 16 (characteristic 3 above) reduces the residencetime of the molten glass bath 22 and tends to increase the size of thegas bubbles 82 that are drawn under the skimmer 50 within theundercurrent 62, while a lower discharge rate R_(D) of the output moltenglass 16 has the opposite effect.

By balancing the three design characteristics set forth above, theskimmer 50 may be sized and positioned so that the gas bubbles 82 thatpass beneath the skimmer 50 within the undercurrent contain at least 95%of smaller gas bubbles that have diameters of less than 0.7 mm or, morepreferably, less than 0.5 mm. The larger gas bubbles having diameters of0.7 mm or greater ascend too quickly and eventually rise to the surface34 of the molten glass bath 22 upstream of the skimmer 50 and burst. Inone implementation of the skimmer 50, in which the glass discharge rate(characteristic 3) is 100 tons per day, the first and second designcharacteristics set forth above may lie within the ranges detailed belowin Table 1 to achieve at least 95% of smaller gas bubbles within theundercurrent 62, although other combinations of characteristics 1-3 arecertainly possible.

TABLE 1 Skimmer Parameters (100 tpd glass discharge rate) ParameterRange S_(D) 180 Feet to 250 Feet T_(D) 3 Inches to 10 InchesUsing the skimmer 50 to separate the gas bubbles 82 so that a contingentof smaller gas bubbles primarily passes beneath the skimmer 50 isadvantageous in one respect; that is, the separation ensures that thesmaller gas bubbles carried by the undercurrent 62 through the submergedpassageway 60 are selectively exposed to the carrier gas 68 and thefining gases produced from the fining agent(s) delivered by the carriergas 68 into the molten glass bath 22.

The housing 18 of the fining vessel 10 may also support one or morenon-submerged burners 84 to heat the molten glass bath 22 and curtail anundesired increase in viscosity. Each of the non-submerged burners 84combusts a mixture of a fuel and an oxidant. The non-submerged burners84 may include one or more sidewall burners 84 a mounted in one or bothof the lateral sidewalls 32 c, 32 d of the housing 18, one or more roofburners 84 b mounted in the roof 28 of the housing 18, or both types ofburners 84 a, 84 b. For example, as shown in FIG. 5, a plurality ofsidewall burners 84 a may be mounted in one or both of the sidewalls 32c, 32 d in spaced relation along the flow direction F between the inlet24 and the outlet 26 of the fining vessel 10. Each of the plurality ofsidewall burners 84 a may be fixedly or pivotably mounted within aburner block. The combustion products 86 a emitted from the burners 84 amay be aimed into an open atmosphere 88 above the surface 34 of themolten glass bath 22 or, alternatively, may be aimed toward the moltenglass bath 22 so that the combustion products 86 a directly impinge thesurface 34 of the molten glass bath 22. The sidewall burners 84 a may bepencil burners or some other suitable burner construction.

In addition to or in lieu of the sidewall burner(s) 84 a, a plurality ofroof burners 84 b may be mounted in the roof 28 in spaced relation alongthe flow direction between the inlet 24 and the outlet 26 of the housing18. In some instances, and depending on the burner design, multiple rowsof roof burners 84 b may be spaced along the flow direction F of themolten glass bath 22, with each row of burners 84 b including two ormore burners 84 b aligned perpendicular to the flow direction F. Each ofthe roof burners 84 b may be a flat flame burner that supplieslow-profile combustion products 86 b and heat into the open atmosphere88 above the surface 34 of the molten glass, or, in an alternateimplementation, and as shown here, each burner 84 b may be a burner thatis fixedly or pivotably mounted within a burner block and aimed todirect its combustion products 86 b into direct impingement with the topsurface 34 of the molten glass bath 22. If a roof burner 86 b of thelatter impingement variety is employed, the burner is preferably mountedin the roof 28 of the housing 18 upstream of the skimmer 50 to suppressfoam build-up.

The non-submerged burner(s) 84 may be configured so that theircombustion products 86 impact the surface 34 of the molten glass bath 22to aid in the fining of particularly foamy molten glass such as, forexample, the glass produced in a submerged combustion melter. Foamyglass with a relatively high amount of bubbles can develop a layer offoam that accumulates on top of the molten glass bath 22. A layer offoam of this nature can block radiant heat flow and, as a result,insulate the underlying glass from any heat added to the open atmosphere88 by non-submerged burners 84 that emit non-impinging combustionproducts. One way to overcome the challenges posed by foam is to breakup or destroy the foam. Direct impingement between the combustionproducts 86 and the top surface 34 of the molten glass bath 22 candestroy and reduce the volume of any foam layer that may develop on topof the molten glass bath 22, which, in turn, can help improve heattransfer efficiency into the molten glass bath 22.

The operation of the fining vessel 10 will now be described in thecontext of fining glass produced in the upstream submerged combustionmelter 14. In general, and referring now to FIG. 1, the submergedcombustion melter (SC melter) 14 is fed with a vitrifiable feed material90 that exhibits a glass-forming formulation. The vitrifiable feedmaterial 90 is melt-reacted inside the SC melter 14 within an agitatedglass melt 92 to produce molten glass. Foamy molten glass 94 isdischarged from the SC melter 14 out of the glass melt 92. The foamymolten glass 94 is supplied to the fining vessel 10 as the input moltenglass 12. The input molten glass 12 combines with and is subsumed by themolten glass bath 22 contained in the fining chamber 20 of the finingvessel 10. The molten glass bath 22 flows along the flow direction Ffrom the inlet 24 of the fining vessel 10 to the outlet 26. As a resultof this flow, the undercurrent 62 of the molten glass bath 22 that flowsbeneath the skimmer 50 is directly exposed to the carrier gas 68 that isintroduced through the nozzles 72 and which carries the fining agent(s).The introduction of fining agents into the molten glass bath 22 directlybeneath the skimmer 50 can selectively target smaller,more-difficult-to-remove gas bubbles, especially if the skimmer 50 isused to separate the gas bubbles 82 introduced into the molten glassbath 22 from the input molten glass 12 based on bubble size.

The SC melter 14 includes a housing 96 that defines an interior reactionchamber 98. The housing has a roof 100, a floor 102, and a surroundingupstanding wall 104 that connects the roof 100 and the floor 102. Thesurrounding upstanding wall 104 further includes a front end wall 104 a,a back end wall 104 b that opposes and is spaced apart from the frontend wall 104 a, and two opposed lateral sidewalls 104 c, 104 d thatconnect the front end wall 104 a and the back end wall 104 b. Theinterior reaction chamber 98 of the SC melter 14 holds the glass melt 92when the melter 14 is operational. At least the floor 102 and thesurrounding upstanding wall 104 of the housing 96, as well as the roof100 if desired, may be constructed from one or more fluid-cooled panelsthrough which a coolant, such as water, may be circulated. Thefluid-cooled panels include a glass-side refractory material layer 106that may be covered by a layer of frozen glass 108 that forms in-situbetween an outer skin of the glass melt 92 and the refractory materiallayer 106. The glass-side refractory material layer 106 may beconstructed from any of the refractories disclosed above for theglass-contacting portions of the upstanding wall 32 of the housing 18 ofthe fining vessel 10.

The housing 96 of the SC melter 14 defines a feed material inlet 110, amolten glass outlet 112, and an exhaust vent 114. As shown in FIG. 1,the feed material inlet 110 may be defined in the roof 100 of thehousing 96 adjacent to or a distance from the front end wall 104 a, andthe molten glass outlet 112 may be defined in the back end wall 104 b ofthe housing 96 adjacent to or a distance above the floor 102, althoughother locations for the feed material inlet 110 and the molten glassoutlet 112 are certainly possible. The feed material inlet 110 providesan entrance to the interior reaction chamber 98 for the delivery of thevitrifiable feed material 90 by way of a batch feeder 116. The batchfeeder 116 is configured to introduce a metered amount of thevitrifiable feed material 90 into the interior reaction chamber 98 andmay be coupled to the housing 96. The molten glass outlet 112 outletprovides an exit from the interior reaction chamber 98 for the dischargeof the foamy molten glass 94 out of the SC melter 14. The exhaust vent114 is preferably defined in the roof 100 of the housing 96 between thefront end wall 104 a and the back end wall 104 b and is configured toremove gaseous compounds from the interior reaction chamber 98. And, tohelp prevent the potential loss of some of the vitrifiable feed material90 through the exhaust vent 114, a partition wall 118 that depends fromthe roof 100 of the housing 96 and is partially submerged into the glassmelt 92 may be positioned between the feed material inlet 110 and theexhaust vent 114.

The SC melter 14 includes one or more submerged burners 120. Each of theone or more submerged burners 120 is mounted in a port 122 defined inthe floor 102 (as shown) and/or the surrounding upstanding wall 104 at aportion of the wall 104 that is immersed by the glass melt 92. Each ofthe submerged burner(s) 120 forcibly injects a combustible gas mixture Ginto the glass melt 92 through an output nozzle 124. The combustible gasmixture G comprises fuel and an oxidant. The fuel supplied to thesubmerged burner(s) 120 is preferably methane or propane, and theoxidant may be pure oxygen or include a high-percentage (>80 vol %) ofoxygen, in which case the burner(s) 120 are oxy-fuel burners, or it maybe air or any oxygen-enriched gas. Upon being injected into the glassmelt 92, the combustible gas mixture G immediately autoignites toproduce combustion products 126—namely, CO₂, CO, H₂O, and anyuncombusted fuel, oxygen, and/or other gas compounds such asnitrogen—that are discharged into and through the glass melt 92.Anywhere from five to thirty submerged burners 120 are typicallyinstalled in the SC melter 14 although more or less burners 120 may beemployed depending on the size and melt capacity of the melter 14.

During operation of the SC melter 14, each of the one or more submergedburners 120 individually discharges combustion products 126 directlyinto and through the glass melt 92. The glass melt 92 is a volume ofmolten glass that often weighs between 1 US ton (1 US ton=2,000 lbs) and20 US tons and is generally maintained at a constant volume duringsteady-state operation of the SC melter 14. As the combustion products126 are thrust into and through the glass melt 92, which create complexflow patterns and severe turbulence, the glass melt 92 is vigorouslyagitated and experiences rapid heat transfer and intense shearingforces. The combustion products 126 eventually escape the glass melt 92and are removed from the interior reaction chamber 98 through theexhaust vent 114 along with any other gaseous compounds that mayvolatize out of the glass melt 92. Additionally, in some circumstances,one or more non-submerged burners (not shown) may be mounted in the roof100 and/or the surrounding upstanding wall 104 at a location above theglass melt 92 to provide heat to the glass melt 92, either directly byflame impingement or indirectly through radiant heat transfer, and toalso facilitate foam suppression and/or destruction.

While the one or more submerged burners 120 are being fired into theglass melt 92, the vitrifiable feed material 90 is controllablyintroduced into the interior reaction chamber 98 through the feedmaterial inlet 110. Unlike a conventional glass-melting furnace, thevitrifiable feed material 90 does not form a batch blanket that rests ontop of the glass melt 92; rather, the vitrifiable feed material 90 israpidly disbanded and consumed by the agitated glass melt 92. Thedispersed vitrifiable feed material 90 is subjected to intense heattransfer and rapid particle dissolution throughout the glass melt 92 dueto the vigorous melt agitation and shearing forces induced by the directinjection of the combustion products 126 from the submerged burner(s)120. This causes the vitrifiable feed material 90 to quickly mix, react,and become chemically integrated into the glass melt 92. However, theagitation and stirring of the glass melt 92 by the direct discharge ofthe combustion products 126 also promotes bubble formation within theglass melt 92. Consequently, the glass melt 92 is foamy in nature andincludes a homogeneous distribution of entrained gas bubbles. Theentrained gas bubbles may account for 30 vol % to 60 vol % of the glassmelt 92, which renders the density of the glass melt 92 relatively low,typically ranging from 0.75 gm/cm³ to 1.5 gm/cm³, or more narrowly from0.99 gm/cm³ to 1.3 gm/cm³, for soda-lime-silica glass. The gas bubblesentrained within the glass melt 92 vary in size and may contain any ofseveral gases including CO₂, H₂O (vapor), N₂, SO₂, CH₄, CO, and volatileorganic compounds (VOCs).

The vitrifiable feed material 90 introduced into the interior reactionchamber 98 has a composition that is formulated to provide the glassmelt 92, particularly at the molten glass outlet 112, with apredetermined glass chemical composition upon melting. For example, theglass chemical composition of the glass melt 92 may be asoda-lime-silica glass chemical composition, in which case thevitrifiable feed material 90 may be a physical mixture of virgin rawmaterials and optionally cullet (i.e., recycled glass) and/or otherglass precursors that provides a source of SiO₂, Na₂O, and CaO in thecorrect proportions along with any of the other materials listed belowin Table 2 including, most commonly, Al₂O₃. The exact materials thatconstitute the vitrifiable feed material 90 are subject to muchvariation while still being able to achieve the soda-lime-silica glasschemical composition as is generally well known in the glassmanufacturing industry.

TABLE 2 Glass Chemical Composition of Soda-Lime-Silica Glass ComponentWeight % Raw Material Sources SiO₂ 60-80 Quartz sand Na₂O  8-18 Soda ashCaO  5-15 Limestone Al₂O₃ 0-2 Nepheline Syenite, Feldspar MgO 0-5Magnesite K₂O 0-3 Potash Fe₂O₃ + FeO   0-0.08 Iron is a contaminant MnO₂ 0-0.3 Manganese Dioxide SO₃  0-0.5 Salt Cake, Slag Se    0-0.0005Selenium F  0-0.5 Flourines are a contaminant

For example, to achieve a soda-lime-silica glass chemical composition inthe glass melt 92, the vitrifiable feed material 90 may include primaryvirgin raw materials such as quartz sand (crystalline SiO₂), soda ash(Na₂CO₃), and limestone (CaCO₃) in the quantities needed to provide therequisite proportions of SiO₂, Na₂O, and CaO, respectively. Other virginraw materials may also be included in the vitrifiable feed material 90to contribute one or more of SiO₂, Na₂O, CaO and possibly other oxideand/or non-oxide materials in the glass melt 92 depending on the desiredchemistry of the soda-lime-silica glass chemical composition and thecolor of the glass articles being formed. These other virgin rawmaterials may include feldspar, dolomite, and calumite slag. Thevitrifiable feed material 90 may even include up to 80 wt % culletdepending on a variety of factors. Additionally, the vitrifiable feedmaterial 90 may include secondary or minor virgin raw materials thatprovide the soda-lime-silica glass chemical composition with colorants,decolorants, and/or redox agents that may be needed, as well as finingagents if such agents are desired to be introduced into the glass melt92 to complement the fining agents introduced into the molten glass bath22 within the carrier gas 68.

Referring now to FIGS. 1, 3, and 5-7, the foamy molten glass 94discharged from the SC melter 14 through the molten glass outlet 112 isremoved from the glass melt 92 and is chemically homogenized to thedesired glass chemical composition, e.g., a soda-lime-silica glasschemical composition, but with the same relatively low density andentrained volume of gas bubbles as the glass melt 92. The foamy moltenglass 94 flows into the fining vessel 10 as the input molten glass 12either directly or through an intermediate stilling or holding tank thatmay settle and moderate the flow rate of the input molten glass 12. Theinput molten glass 12 is introduced into the fining chamber 20 throughthe inlet 24 and combines with and is subsumed by the molten glass bath22. The blending of the input molten glass 12 with the molten glass bath22 introduces the gas bubbles 82 into the glass bath 22. These gasbubbles 82 are removed from the molten glass bath 22 as the glass bath22 flows in the flow direction F from the inlet 24 of the fining vessel10 to the outlet 26.

As the molten glass bath 22 flows in the flow direction F, theundercurrent 62 of the glass bath 22 flows beneath the skimmer 50through the submerged passageway 60 to navigate molten glass past theskimmer 50. The undercurrent 62 is selectively and directly exposed tothe fining agent(s) that are introduced into the undercurrent 62 fromthe carrier gas 68, which, in this particular embodiment, produces arising row of carrier gas effervescence upon being dispensed into themolten glass bath 22. The fining agent(s) react with the molten glass torelease fining gases into the undercurrent 62 and the portion of themolten glass bath 22 downstream of the skimmer 50. These fining gasesremove the gas bubbles 82 that pass through the submerged passageway 60by accelerating the ascension of the gas bubbles 82 or causing the gaswithin the bubbles 82 to dissolve into the glass matrix of the moltenglass bath 22. In that regard, the skimmer 50 may be used to separatethe entrained gas bubbles 82 introduced into the molten glass bath 22 asdiscussed above to ensure that most of the gas bubbles 82 that passbeneath the skimmer 50 are smaller gas bubbles having a diameter of 0.7mm or less or, more preferably, 0.5 mm or less. As a result, the densityof the molten glass bath 22 increases along the flow direction F of theglass bath 22, and the amount of the fining agent(s) introduced into themolten glass bath 22 may be limited to what is needed to effectivelyremove the smaller gas bubbles that pass beneath the skimmer 50.

The output molten glass 16 is removed from the outlet 26 of the finingvessel 10 and has a second density and a second concentration ofentrained gas bubbles. The second density of the output molten glass 16is greater than the first density of the input molten glass 12, and thesecond concentration of entrained gas bubbles of the output molten glass16 is less than the first concentration of entrained gas bubbles of theinput molten glass 12. For instance, the output molten glass 16 may havea density of 2.3 gm/cm³ to 2.5 gm/cm³ and a concentration of entrainedgas bubbles ranging from 0 vol % to 1 vol % or, more narrowly, from 0vol % to 0.05 vol %, for soda-lime-silica glass. The output molten glass16 may then be further processed into a glass article such as a glasscontainer. To that end, the output molten glass 16 delivered from theoutlet 26 of the fining vessel 10 may have a soda-lime-silica glasschemical composition as dictated by the formulation of the vitrifiablefeed material 90, and a preferred process 150 for forming glasscontainers from the output molten glass 16 includes a thermalconditioning step 152 and a glass article forming step 154, asillustrated in FIG. 8.

In the thermal conditioning step 152, the output molten glass 16delivered from the fining vessel 10 is thermally conditioned. Thisinvolves cooling the output molten glass 16 at a controlled rate toachieve a glass viscosity suitable for glass forming operations whilealso achieving a more uniform temperature profile within the outputmolten glass 16. The output molten glass 16 is preferably cooled to atemperature between 1000° C. to 1200° C. to provide conditioned moltenglass. The thermal conditioning of the output molten glass 16 may beperformed in a separate forehearth that receives the output molten glass16 from the outlet 26 of the fining vessel 10. A forehearth is anelongated structure that defines an extended channel along whichoverhead and/or sidewall mounted burners can consistently and smoothlyreduce the temperature of the flowing molten glass. In anotherembodiment, however, the thermal conditioning of the output molten glass16 may be performed within the fining vessel 10 at the same time themolten glass bath 22 is being fined. That is, the fining and thermalconditioning steps may be performed simultaneously such that the outputmolten glass 16 is already thermally conditioned upon exiting the finingvessel 10.

Glass containers are formed from the conditioned molten glass in theglass article forming step 154. In some standard container-formingprocesses, the conditioned molten glass is discharged from the spout 38at the end of the fining vessel 10 or a similar device at the end of aforehearth as molten glass streams or runners. The molten glass runnersare then sheared into individual gobs of a predetermined weight. Eachgob is delivered via a gob delivery system into a blank mold of a glasscontainer forming machine. In other glass container forming processes,however, molten glass is streamed directly from the outlet 26 of thefining vessel 10 or an outlet of the forehearth into the blank mold tofill the mold with glass. Once in the blank mold, and with itstemperature still between 1000° C. and 1200° C., the molten glass gob ispressed or blown into a parison or preform that includes a tubular wall.The parison is then transferred from the blank mold into a blow mold ofthe glass container forming machine for final shaping into a container.Once the parison is received in the blow mold, the blow mold is closedand the parison is rapidly outwardly blown into the final containershape that matches the contour of the mold cavity using a compressed gassuch as compressed air. Other approaches may of course be implemented toform the glass containers besides the press-and-blow and blow-and-blowforming techniques including, for instance, compression or other moldingtechniques.

The final container formed within the blow mold has an axially closedbase and a circumferential wall. The circumferential wall extends fromthe axially closed base to a mouth that defines an opening to acontainment space defined by the axially closed base and thecircumferential wall. The glass container is allowed to cool while incontact with the mold walls of the blow mold and is then removed fromthe blow mold and placed on a conveyor or other transport device. Theglass container is then reheated and cooled at a controlled rate in anannealing lehr to relax thermally-induced constraints and removeinternal stress points. The annealing of the glass container involvesheating the glass container to a temperature above the annealing pointof the soda-lime-silica glass chemical composition, which usually lieswithin the range of 510° C. to 550° C., followed by slowly cooling thecontainer at a rate of 1° C./min to 10° C./min to a temperature belowthe strain point of the soda-lime-silica glass chemical composition,which typically lies within the range of 470° C. to 500° C. The glasscontainer may be cooled rapidly after it has been cooled to atemperature below the strain point. Any of a variety of coatings may beapplied to the surface of the glass container either before (hot-endcoatings) or after (cold-end coatings) annealing for a variety ofreasons.

The glass melting, fining, and glass article forming processes describedabove are subject to variations without detracting from their purposesor objectives. For example, as shown in FIGS. 3-4, one or more skimmers160 formed of a refractory material may additionally be included in thefining vessel 10 downstream of the skimmer 50 described above. Each ofthe additional skimmers 160 may individually be the same type of skimmeras described above in that a carrier gas that includes suspendedparticles of one or more fining agents may be introduced directlybeneath the additional skimmer 160. Alternatively, each of theadditional skimmers 160 may be a conventional skimmer that is simplysubmerged partially into the molten glass bath 22 without any carriergas and suspended fining agent particles being introduced into the glassbath 22 from below. If additional skimmers 160 are included in thefining vessel 10, in many instances the number of additional skimmers160 will be somewhere between one and three.

There thus has been disclosed a method of fining glass that satisfiesone or more of the objects and aims previously set forth. After beingfined, the molten glass may be further processed into glass articlesincluding, for example, glass containers. The disclosure has beenpresented in conjunction with several illustrative embodiments, andadditional modifications and variations have been discussed. Othermodifications and variations readily will suggest themselves to personsof ordinary skill in the art in view of the foregoing discussion. Forexample, the subject matter of each of the embodiments is herebyincorporated by reference into each of the other embodiments, forexpedience. The disclosure is intended to embrace all such modificationsand variations as fall within the spirit and broad scope of the appendedclaims.

1. A method of fining glass, the method comprising: supplying inputmolten glass into a fining chamber of a fining vessel, the input moltenglass combining with a molten glass bath contained within the finingchamber and introducing entrained gas bubbles into the molten glassbath, the input molten glass having a density and a concentration of gasbubbles; flowing the molten glass bath through the fining chamber in aflow direction, the molten glass bath having an undercurrent that flowsbeneath a skimmer, which is partially submerged in the molten glassbath, and through a submerged passageway defined in part by the skimmer;and introducing a carrier gas into the undercurrent of the molten glassbath directly beneath the skimmer, the carrier gas comprising suspendedparticles of one or more fining agents.
 2. The method set forth in claim1, wherein the carrier gas includes a main gas that supports thesuspended particles of the one or more fining agents.
 3. The method setforth in claim 2, wherein the main gas is air or nitrogen.
 4. The methodset forth in claim 1, wherein the one or more fining agents includes asulfate that decomposes to release O₂ and SO₂ fining gases.
 5. Themethod set forth in claim 1, wherein the one or more fining agentsincludes sodium sulfate, Cr₂O₃, WO₃, carbon, aluminum, a carbonate,silicon carbide, oxidized metal powder, or combinations thereof.
 6. Themethod set forth in claim 1, wherein the fining vessel includes ahousing that defines the fining chamber, and wherein the carrier gas isintroduced into the molten glass bath from a plurality of nozzles thatare supported within a floor of the housing.
 7. The method set forth inclaim 6, wherein the plurality of nozzles are spaced apart along a widthof the fining chamber beneath the skimmer to provide a row of carriergas effervescence that extends transverse to the flow direction of themolten glass bath and rises upwards from the floor of the housing. 8.The method set forth in claim 1, wherein the input molten glass has asoda-lime-silica glass chemical composition.
 9. The method set forth inclaim 1, further comprising: discharging output molten glass from thefining vessel, the output molten glass having a density that is greaterthan the density of the input molten glass and further having aconcentration of gas bubbles that is less than the concentration of gasbubbles of the input molten glass.
 10. A method of producing and finingglass, the method comprising: discharging combustion products from oneor more submerged burners directly into a glass melt contained within aninterior reaction chamber of a submerged combustion melter, thecombustion products discharged from the one or more submerged burnersagitating the glass melt; discharging foamy molten glass obtained fromthe glass melt out of the submerged combustion melter; supplying thefoamy molten glass into a fining chamber of a fining vessel as inputmolten glass, the input molten glass combining with a molten glass bathcontained within the fining chamber and introducing entrained gasbubbles into the molten glass bath, the input molten glass having adensity and comprising up to 60 vol % bubbles; flowing the molten glassbath through the fining chamber in a flow direction, the molten glassbath having an undercurrent that flows beneath a skimmer, which ispartially submerged in the molten glass bath, and through a submergedpassageway defined in part by the skimmer; introducing a carrier gasinto the undercurrent of the molten glass bath directly beneath theskimmer, the carrier gas comprising suspended particles of one or morefining agents; and discharging output molten glass from the finingvessel, the output molten glass having a density that is greater thanthe density of the input molten glass and further comprising less than 1vol % bubbles.
 11. The method set forth in claim 10, wherein the carriergas includes a main gas that supports the suspended particles of the oneor more fining agents.
 12. The method set forth in claim 11, wherein themain gas is air or nitrogen, and the one or more fining agents includessulfate particles suspended in the main gas, the sulfate particlesdecomposing in the molten glass bath to release O₂ and SO₂ fining gases.13. The method set forth in claim 10, wherein the one or more finingagents includes sodium sulfate, Cr₂O₃, WO₃, carbon, aluminum, acarbonate, silicon carbide, oxidized metal powder, or combinationsthereof.
 14. The method set forth in claim 10, wherein the glass melt inthe submerged combustion melter and the molten glass bath in the finingvessel have a soda-lime-silica glass chemical composition.
 15. Themethod set forth in claim 14, further comprising: forming the outputmolten glass discharged from the fining vessel into at least one glasscontainer having an axially closed base and a circumferential wall, thecircumferential wall extending from the axially closed base to a mouththat defines an opening to a containment space defined by the axiallyclosed base and the circumferential wall.
 16. A fining vessel for finingglass, the fining vessel comprising: a housing that defines a finingchamber, the housing having a roof, a floor, and an upstanding wall thatconnects the roof and the floor, the housing further defining an inletto the fining chamber and an outlet from the fining chamber; a skimmerextending downwards from the roof of the housing towards the floor ofthe housing and further extending across the fining chamber betweenopposed lateral sidewalls of the upstanding wall, the skimmer having adistal free end that together with corresponding portions of the floorand upstanding wall defines a submerged passageway; and a plurality ofnozzles supported in the floor of the housing directly beneath theskimmer, each of the nozzles being configured to dispense a carrier gasinto the fining chamber, the carrier gas including a main gas thatcontains suspended particles of one or more fining agents.